Electric furnace.



"L THOU.

LEGTR PRHAGE.

APPLICATION FILED SEPT. 1, 1909.

Patellis@ Ela?. l, 19M).

5 SHEETS-SHEET 1.

J. THOMSON.

ELECTRIC FURNAGB.

APPLICATIONv FILED SEPT. 1, 1909,

Patented Mar. 1, 1910.

2 T E E H s S T E E H S 5 Mventor by M m,

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fjA-ttesrtj l (L THOMSON:

Hmmm@ Emmen n APPLIATION FILED SEPT. 1, 1969. @sg/@E Patented Mar. l,1910.

5 SHEETS-SHEET 3 I I @WL mma J. THOMSON.

ELECTRIC FURNAGE.

APPLIGATION FILED SEPT. 1, 1909.

Patented Mar. 1, 19.10.

5 SHEETS-SHEET 4.

@ML (MM Affili.,

JOHN THOMSON,

OF NEW YORK, N. Y., ASSIGNOR TO IMBERT PROCESS COMPANY, OF

NEW YORK, N. Y., A CORPORATION OF NEW YORK.

vELECTRIO FURNACE.

Specification of Letters Patent.

Applieationled September 1, 1909.

Patented Mar. i, 1910.

serial No. 515,698.

S'J all whom it may concern.'

Be it known that I, JOHN THOMSON, a cicizen. of the United States, and aresident of the borough of Manhattan, of the city of New York, in thecounty and State of New York, have invented certain new and usefulImprovements in Electric Furnaces, of which the following is aspecification, refer ence being-had to the accompanying drawings,forming a part hereof.

This invention relates particularly to im. provements inv resisters ofelectric furnaces and to their arrangement and disposal in the furnacechamber with a View to-most effectually realizing the widest range ofadaptability and the highest thermal efficiency.

One of the principal objects of the inven tion is to provide a resister,which, while being composed of a plurality of elements, is selfsupporting; that is one which does not require any extraneous means ofsupport. between the terminals, whereby the resister may be entirelyfree from or out of contact with all parts of the refractory and, infact, uspended in space within the furnace cham- Another object of theinvention is to provide a resister which may have its resistivityincreased or decreased in different zones whereby to correspondinglychange the current densit within itself; which shall be capable oflieing formed by the established methods of manufacture; which shall bereadily applicable to various types of furnace and to which the furnaceand its heating chamber are conformable in a manner to derive both themaximum of temperature ad the. highest rate of delivery, or volume, fheat-units in a given time from a given amount of energy.

in` accordance with the present. improvements, the foregoing is realizedby forming,

the resister, preferably of carbon, from a l plurality of partsconstructed and arranged to interlock one with the other, or one or morewith others, and also to interlock with or be sustained by theterminals, in such manner that the resister is in free space and may bebuilt either above, or below, or atE the sides of a heating chamber; andfurthermore, the cordinative construction of the? furnace chamber issuch that t-he delivery of i the heat waves from all portions of the eX-posed surfaces of the resister is realized in i useful effect upon thecharge with the minimum of dynamic loss.

l`n the drawings: Figure l is a plan View of 'a furnace embodying theinvention, with the cover removed. Fig. 2 is a longitudinal centralsection, the planeof the section being indicated by the line 2 2 in Fig.l. Figs. 3 and 4 are transverse central sections,

left and right, respectively, the plane of the sections being indicatedbythe line 3 4 in Figs. 1 and 2. Fig. 5 is a transverse central sectionand Fig. 6 is a longitudinal central section of a furnace showingmodifications. Fig. 'l' is a plan view and Fig. S is a vertical centralsection of a furnace showing other modifications. Fig. 9 is an enlargeddetail view of the resister sections and the terminals, to-betterillustrate the application thereof, as shown in the preceding figures.Fig. 10 is an enlarged detail view of a resister applied in a modifiedmanner, and Fig. 11 is a diagrammatic detail indicating some of thevarious forms of construction of elements which may be employed to buildthe resister.

Referring first to Figs. 1 4 inclusive and to Figs. 9 and 10, oneembodiment of the invention will first be described in connection with,the particular type of furnace shown in these figures. Here, the mainbody a of the furnace is provided with a removable cover b containing anopening u for charging or for visually inspecting the interior of thefurnace, and the resister is a compound one having two sections D andD". which are connected up in series, confined between the terminals cand e at one end and the connector-piece e2 at. the other end.

Each section of the iesisteiwvill be seen to consists of a. plurality ofgrooved plates d laidn transversely thereof and the opposing faces of'ivhich are so disposed as to prevent a staggered ariangement` of thewhole;'and

in the figures under present consideration,

each resister` element may be likened to a series of round rods laidtogether lengthwise but having rounded or neck-likejoints along theintersections, thus presenting the form of la iuted plate.' Manifestlywhen such plates are laid together, with the rounds of one plate in thehollows of another the contacts will be in lines, and when a series ofsuch plates ne set between terminals, or a terminal and a connector,having correspondina' llutings, as shown, and held against. displacementendwise, the several parts are interlockcd and the resisterras a` wholeis seltsustaimng, its weight and endthrust being` taken whol ly by thesaid terminals. As comparatively little end-pressure is necessary tomaintain the lines of contact along all of the convolutions7 it Will nowbe apparent that. with such a keyed structure a wide range ot'electrical contact; resistance in ay he obtained and that, beinsc`independent of position for its support, it. can he built in variousforms and applied to many types of furnaces. Thus, in Figs. l to 4t, theresister shown si pended in clear space above the i; in jfii. and (S theresister is sus` ed below the retort c, while in Figs. T and f3, theresister is suspended within a circular -furnme casing', in tourvertical sections.l` torni] .fr a hollow square within which av crucibleas c, may be set. ln this instance il e convolutions ol the resisterplates would be .isc o't' the plates instead of lengthwi llnt while thedescribed arrangement ot' having the resister suspended by the ter--minais is regarded as the pret'erz'ible this is not, au inclispensahle'lcature and in 't'act there may be circ!nnstances where the said su n4Vn might equally well be upon the tui-nace walls direct'. Thus, theretractories c, r7 l to (L shown in Atull lines, which act as theluunary supports tor the teru1inals, and as secondary supports tor theresi er.y siini'ily require to be extended inwai-diy7 as shown by thedotted outlines r2, il :i and t5, when the .ster would be primar'lysupported at each end thereby; and in this wise the terminals may bearranged to be removed without iutert'ering i, h the resister.

.is has already been pointed out in another application i Letters Patenttiled itflay 13, lit/Dt `tlerial No. s955585, in order to main-- lain apractically constant pressure upon the iarbon. which essential to thecontrol ol thc electro-therinacy7 the emi-pressure required toniaintaiii the tinted plates is produced through the intervention ofsuitably mounted springs c?l` liigs. l, 2 and 6, actuated by :uljustinglscrews c", or in the instance of Figs. 7 and 8 by yield- 'ing` steelbands c acting' resiliently against the brick-work. ln this wise7 theexact amount of pressure can readily be applied and also such an extentot resiliency that the expansion or contraction ofthe resister cantal-fe place withoutsensibly changing its density. lihen a compoundresister is used. connected in series, two screw-actuated springs arepreferred7 as shown in Fig. l, whose outer thrust is taken by the barel" which contains the adjusting screws. In thisl instance each sping islocated to impart' its thrust through a sliding refractory cinniingingagainst the connector e2 along interlock ot the] l l l l l l i l l v andbot'` the central axis ot each section otl the rw sister. Now, byplacingslidablc carbon rods cw capable ot' being,` impinged when desiredagainsty the connector and a rolt-n'ietcr, or nie-- ters, as c,connected by a shunt circuit hetween these rods and the inain circuit,it can be ascertained at. once and at any time it' the rate ot"generation ot' energy in both sect ionsI oitl the resister is the same,and il not the rcsistance ot' the said sections can be made thiI same bv proper manipulation ol' thc spring' tension` lllithout. someconvenient means olj this kind the rate ot generation ol energy in onesection might be much greater than in the other and the endurance ol"the whole would be that ot the overloaded member.

Another advantag'cmls Vleature ot this inrei-locking` resister system isthat any side ot a resister may readily he given greater conlnessionthan the opposite side` thereby corres-poni ingly increasing' thecurrent dein sity and the temperature. e'aiin when a resister isdisposed along a hoi izontal vplane` with inist sutlicicnt eiuhpressureto ma he contacts between the tlut'ingfs, its upper portion. duc to itsweight, will be under compression whilc its lower portion will be intension. tending like an arch to separate. .\n cxactly neutralcondition, or an exi-,css` can readily be el'lectcd by the simplecxpedien shown in Fig. i), wherein thc 'tacos olt the terminals areslightly beveled so that when the terminals approach cach otherhorizontally, the pressure will be greater. or more intense. along' thelower line un than the upper n ln practice the actual amount ol' theditlierenee in spaciin;` between the top om ot' cach plate is ordinaril\v \'cr slight.y say 'from .O02 to .O05 inch: and may be raged with theutmost exactness b v the angle given to the terminals.

lt will be observed in Fin". lninals and the connector are wider thanthe main portion ol the resister and that rrsisterplatcs d are providedto connect therewith whose widths are approximatcly equal to that ot'the said terminals and connector: the object` and :nlvautaiye ol' thisbeine' to obtain the largest possible arca ot contact and therebydeliver the current. into the resister with the least possible drop involtage trom the line connection.

that thc ter A construction ot the resistenis .--ho\\'u in Fig'. l() inwhich the inlerloclied plates are stacked at a considerable angle to thehorizontal, Q2 degrees, as denoted in the drawing. This involves the useot a. kevlCS llt)

unlike an arch, the lineal length of the resister elements, above andbelow, are equa-l, the lineal difference being entirely compensated inthe key, which would ordinarily be of puregraphite; and consequently thevari- 'ation in its resistance through top or bottom would beinappreciable.

Because of its strength, rigidity and ease of manufacture, the ilutedresister plate, with staggered interlock, is regarded as the preferableform; but, will now be shown, various modifications thereof can be made,whereby to meet any or all practical requirements. Thus, in Figs. 5 and6, the resister is composed of plates Z3 having V- grooves and betweenthe said grooves sepa. ratetubes, as Z4 are interposed. Here each tubeacts as akey and yields four lines of pressure contact between each pairof plates. This combination possesses the obvious ad- 'antage of havingan exceedinglylarge area of radiating surface. In the variousmodiications illustrated in Fig. 1l, the tubes d* are shown asinterlocking shallow squareshaped grooved plates d5 and d in a mannerwhereby six lines of pressure Contact are shown for each tube; roundrods Z7 are' here shown, substituting the tubes; balls, (ZS may take theplace of either and .corrugated plates d1, d, d may be employed, ofuniform thickness, where the combination of dl" and d will obtainlinecontacts. Finally, should the requirement arise of obtaining' aninterlocked resister of the lowest. possible resistivity, this may herealized by combining the two similarly V-groored plates dg, or thecorrugated plates d and d as inthese instances the area and intimacy ofContact would be greater than that of flat plates of correspondmg facedimenlt may be pointed out with respect to the arrangement of partsshown in Fig; 6 that this type of furnace readily lends itself to given0E by the charge would actdetrh. Thus, by

mentally on the carbon resister. simply closing theI side spazes at thetop,

carbid 4or the like, shown in dotted' lines y,

`the resister would then be etectively contained in a chamber distinctand separate from that of the charge.

W'hen a compound resister is employed,

in seri and 'arranged after the manner i shown in Figs. l, 2, and 4, itis preferable to use a connector made of Acheson graphite; but theleading-out terminalsl are preferably of amorphous carbon. Theladvantage'is in the higher electrical and thermal conductibility of thegraphite, inside of the furnace, and the lower thermal conductiblhty ofthe carbons to the exterior of the furnace. At normal. temperature theelecay thin plates of recrys allized silicon f toward the bath, retortor Crucible` trical resistance of pure graphite is about.

four times less than amorphous carbon, for like sections; but at hightemperatures th'c difference is considerably less. Still, thedifference, even at the best, is not negligible when thousands ofamperes are to be delivered to the resister. This objection is largelyovercome by making the inner portions of the terminals, where they arein contact with the resister, as from i' to s, of graphite, and theouterv portions, as from s to p, of carbon. This can be. accomplished bygraphitizing only that portion of the terminals which are to lic insideof the furnace, or by suitably jointing two blocks, one of graphite andthe other of carbon.

It will be perceived that if the register plates are under an equaldegree of contact between their various lines of inipingement-acondition which the construction already described' can readily obtainand indefinitely continue-that all parts of its sur face will similarlyradiate heat; and also that the longitudinal spaces alongl thelinecontacts of the tlutings afford an exceedingly effective egress forthe heat from every porl tion of the incandescent mass. To realize theutmost efficiency of this condition is the complementary feature of thedesign, and consists in forming the inner walls of the heating chamberso as to present a surface of incidence which shall be less or more thana right angle to the emitted heat of the resister, thus rendering theincipient energy less effective. to in'ipart heat to the furnace ll andmore effective to increase the temperature of the charge. rlherefore, inFigs. 2, 3. 4, 5, 6 and 8, where the arrows :1f indicate heat wavesradiating directly from the resister and the arrows .z indirect orrefracted waves, theimpingement of-the heat upon the bath, retort orcrucible is lgenerally shown as in direct lines, the most effectivepossible for the contemplated purpose; while the surrounding andovertopping walls are appropriately curved to deflect the direct heatwaves received fromv thc various surfaces of the resister and cause themto continue their movement, although with lessened intensity,,downwardly or upwardly And the consequence of this construction, whichis entirely feasible to realize 'in practice, is a material increase inthermal etli'ciency and endurance of the refractories.

From the foregoing, it. will be understood how the invention may beembodied in various types of furnaces. In the several coustructionsillustrated herein, the saine reference letters have been used to referto corresponding parts, so that a detailed descrip-- tion in the case ofeach of the furnaces specitically alluded to has been unnecessary.Moreover, it. may be noted here that. in all of the illust-rations ofthe present case, the

Clt

resister has been shown in compound `lorln with its sections connectedup in series. ln such instances. the connector-piece between any twosections is7 111echanically considered at least. the equivalentl of aterminal and should be so understood in reading the claims.

It only remains to be stated that the interlocking plate resister may beused. retaining i' many ot the ad fantages that have been pointed out inthe foregoing, by being sup ported along its sides` either continuouslyor at one or more locations, or at one or both sides. For instance7 suchan arrangement would be the preferable when Very light line-contacts aredesirable.

l claim as my invention:

l. resister for an electric furnace coinprisiug a plurality ofinterlocking resista nee 1' elements.

resister 'lor an electric furnace con1- pr1s1ng a lnral1tp\' otinterlocking resistVl plates.

2l. resister for an electric furnace coinprising a plurality ot tintedplates.

1li. resister for an electric lurnace. coniprifng a plurality ot'.interlocking carbon plates.

53. A resister for an electric furnace romprising a plurality ot'grooi'ed plates arranged to interlock with each other.

' t3. n electric furnace comprising a. plurality o in a direct linebetween the terminals and supported entirely free of the refractory.

In an electric furnace, in combination having a resister; l.' elementsdisposed 13. An electric fi'irnacc haring resister 'composed ofseparable resistance parts interlocked between themselves and theterminals.

lll, An electric furnace having corne pound resister adapted to be connetet. parallel or in series and composed sep* arable parts interlockedbetween themselves, the terminals and the connector.

15. An electric furnace having an inter locked resister engaged by theterminals and suspended thereby in a direct line.

lo. In an electric furnace, a resister coinposed of grooved plates heldtogJt-her by the terminals.

17. in an electric furnace, a resister com posed ot' groored plates,assembled in staggered relation and held together by the ter-- minals,

1S. in an electric furnacet a res posed o'l grooved pli-ttes. and mea slist l' in. the grooves to interlock the s: all being held tog ther bythe it 'annals 1Q. ln an electric furnace.) aA plm-9.1i@ fr.-1nterlock1ng res1stance elements. and te electric furnace. a plurality f1' interlocking resistance element a 1' the r sister, and terminalswhose faces are with the terminals, a, resister having afplu- '1 ralityot`elcn1ents suspended .from and ina direct line between the terminalsand sel l sustaining so as not to require any extraneous nieans ot'support other than the ler ininals.

S. iin electric furnace havinga resirter composed ot separableinterlocking re. ance, plates arranged transversely thereot.

9. An electric furnace havinga resister composed ot' separable groovedplates arranged transversely thereof, the said resister being supportedwholly .trom its ends.

l0. An electric 't'urnacc having a resister comprising a plurality ot'interlocking re.- sistance elements and terminals ateach end thereofacting` to maintain the interlocking of and thereby to support theelements.

ll. An electric furnace haring a resister coinln'ishig a plurality ot'interlockingresistance plates mounted face to tace and means to supportthe resister by maintaining a, thrust lengthwise of the same.

l2. An electric furnace having a resister comprising a plurality ofgrooved plates mounted face to face and terminals at each end of theresister adapted to exert a thrust to keep the plates interlocked witheach other. Y

wider than the main portion or the said resister.

Q2. ln an electric turna t.. resister and terminals by ai .it l en whthe resister is arranged to be sel," sustaini D in a direct line, thesaid terminals having the planes of their faces disposed to impart pr ssure at one or the other sides et the neutra;A axis of said resister.

fin electric furnace having a resister composed ot' interlocking parts,terminals therefor and resilientor reactive means to clamp .theterminals.

24. Au electric furnace having a resister composed of interlocking partsmounted in a plurality of sections between electrical connections, theend pressure on each section being separately adjustable.

25. An electric furnace having an interlocking resister mounted in aplurality of sections between terminals, and a movable electrode orelectrodes for connecting each of said sections in a shunt circuitwhereby to separately measure its resistivity under actual Workingconditions.

26. An electric furnace having a resister mounted therein the innersurface or surfaces ot' the furnace being irregularly curved er slopedso tha the amge @if refraction herefromshai be lese er mme nau a rightangle to che iiie of izipingement of ihe emitted heet Waves. o' 27. Alleiectrc funace leaving .e resister mounted. che i ie hem. she charge orits centenef by eli eet iwimien imm a portion thereof, 'the une' euface01 sufaees ef the furmee being ezmed with irl-@grainy curves e rediateheat from Hm ohei pori es of ti siste? in dii @tiene feee from that i-eiines apr/ict.

meets eve comin-ed? one ef the efmiuas it ing between beh ermmais.

in eecie fur-na e having a ifesiste` compese ci 'pzisfaii'by of greevedaes ieiiiilmis iieween which fffiie plaies are con iied e f bem-ingagainst means to erguet ehe reuiese set 60Min,

t; resister 03% eemeuf ispese n wipe-sied enbetween which die te muy ehedistance tirey free of the rernctory, :1nd yieciing means to retain eueof the termiunis.

31. n an electric furnace, in Combination Y with Jl:he temuinais,resister comprising e plurality of elements disposed 'between theterminals aud supported wholly thefeby, and. means te permit one if theseminels to have e limited range of movementy te compensate for il'xeexpansion and contraction of the ye- "ei demente due 'to them-ual@hangt-2,

fm eleetiic furnace having terminal Suppoifts extending under lieresise.

in eleerc furnace having refrac- 'zeles i0 support lie iteri'ninas, saidrefraeories beim; extended underneath the ends'of the resister izosupport ihe sii-me.

34. In en electric furnace uv iesisel' having a piusf'aity ef ucrlockedDiembeis and adapted te be Supported wholly from its ends, terminalstherefor .and @Xteued terruina supporta This specieeticn signed andwitnessed this 31st dey o' August, A. D., 1909.

JGHN TH I'SO. Signed in the presence ef-- M.. JReLLNe, G. MCGRANN.

